Condenser circulating cleaning method and cleaning system

Abstract

The invention relates to the technical field of condenser cleaning, in particular to a condenser circulating cleaning method and system. By adopting the circulating cleaning system and optimizing the cleaning process and parameters, the descaling efficiency of the condenser is remarkably improved, equipment corrosion is reduced to the greatest extent, meanwhile, the utilization rate of a cleaning agent is greatly increased, chemical consumption and waste liquid discharge are reduced, and the environmental load and treatment cost in the cleaning process are reduced from the source.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of condenser cleaning, in particular to a condenser circulating cleaning method and a cleaning system. BACKGROUND

[0002] The condenser is a key equipment in the steam power cycle system, and its main function is to condense the exhaust steam discharged by the steam turbine into water, so as to establish and maintain a high vacuum at the exhaust end of the steam turbine, which is crucial to the thermal efficiency of the entire unit. A typical shell-and-tube condenser realizes heat exchange through a large number of heat exchange tubes installed on the tube plate, and the cooling water flowing in the tubes takes away the latent heat of condensation of the steam outside the tubes.

[0003] However, during operation, impurities in the circulating cooling water are prone to fouling on the inner wall of the heat exchange tube. The scale layer has very poor thermal conductivity, which can seriously hinder heat transfer, leading to deterioration of the vacuum degree of the condenser, and thus causing the thermal efficiency of the unit cycle to decrease and the operating cost to increase. In addition, the scale layer can also induce under-deposit corrosion of the heat exchange tube, shortening the service life of the equipment.

[0004] At present, although there are prevention and control methods such as chemical cleaning and gel ball cleaning, these methods have limited cleaning effect on hard scale that has already formed, or require a large amount of chemicals and water resources, and there is an urgent need to develop a cleaning method with high descaling efficiency and low environmental impact and consumption.

[0005] In view of this, the present application is proposed. SUMMARY

[0006] The purpose of the present application is to provide a condenser cleaning method and system with higher descaling efficiency and more environmental protection and lower consumption.

[0007] The present application provides a condenser circulating cleaning method, characterized in that it comprises the following steps: S1: filling the steam side of the condenser with condensate water; S2: preparing a cleaning solution in a cleaning tank, the cleaning solution comprising acid and corrosion inhibitor; S3: pumping the cleaning solution into the condenser through an acid supply pipeline to fill the water side of the condenser with the cleaning solution; S4: cleaning at a cleaning solution flow rate of 0.1-0.25 m / s, and recycling the generated acid return liquid to the cleaning tank or the condenser for circulation; S5: supplementing acid when the acid concentration in the cleaning solution is lower than a specified value, the acid supplementing comprising first adding the corrosion inhibitor and then adding the acid after uniform circulation; S6: stopping acid cleaning when the acid concentrations in the acid supply pipeline and the acid return pipeline approach equilibrium, the acid concentration is continuously stable for 2 hours, and / or no gas is generated in the acid return liquid.

[0008] In some embodiments of the present application, the temperature of the condensed water is ≯ 25℃.

[0009] In some embodiments of the present application, the cleaning solution comprises 3%-5% nitric acid and 0.2%-0.5% corrosion inhibitor, and the specified value of the acid concentration in the cleaning solution is 3%. Preferably, the cleaning solution comprises 3%-5% nitric acid and 0.3% Lan-826 type corrosion inhibitor.

[0010] In some embodiments of the present application, the pressure during the cleaning process should be kept ≯ 0.1 MPa.

[0011] In some embodiments of the present application, the acid concentration is detected every 30 minutes during the cleaning process, and the acid concentration is detected every 10 minutes near the end of the cleaning process. For example, the acid concentration of the cleaning solution in the cleaning tank or the acid supply pipeline and the acid concentration of the acid return solution in the acid return pipeline can be detected.

[0012] In some embodiments of the present application, the corrosion degree of the cleaning process is monitored by a corrosion indicating pipe arranged in the water chamber of the condenser. For example, the condenser pipe test ring can be used as the corrosion indicating pipe.

[0013] In some embodiments of the present application, multiple condensers are cleaned simultaneously, and when the acid concentration of the generated acid return solution is higher than the specified value, the acid return solution is recovered to other condensers for recycling.

[0014] In some embodiments of the present application, the method further comprises, before step S1, filling the steam side of the condenser with desalted water and checking for leaks. If a leaking heat exchange tube is found, plugging measures are taken.

[0015] In some embodiments of the present application, the method further comprises, before cleaning, checking for leaks and defects in the cleaning system. Industrial water is injected into the cleaning system, and a circulating pressure test is performed by starting the cleaning pump. If there is a leakage site, effective plugging is taken.

[0016] In some embodiments of the present application, the method further comprises, after stopping the pickling, flushing the cleaning system. For example, industrial water is injected into the cleaning system to flush the cleaning system. The flushing is stopped when the pH value of the water is 6-9, and the cleaning system is disconnected from the condenser system.

[0017] In some embodiments of the present application, the method further comprises, after step S6, flushing the water side of the condenser with circulating water. The circulating water outlet and inlet doors are opened, and the water side of the condenser is flushed with circulating water. After the flushing is completed, the condenser manhole door is opened to check the pickling effect and check whether the condenser heat exchange tube is leaking for plugging and defect elimination.

[0018] The application also provides a condenser circulating cleaning system, characterized in that the cleaning system comprises a cleaning tank, a cleaning pump, an acid supply pipeline and an acid return pipeline, The cleaning pump inlet is connected with the cleaning tank, and the cleaning pump outlet is connected with the inlet end of the acid supply pipeline; The lead-in pipe and the outlet end of the acid supply pipeline are respectively connected with a plurality of condenser water chambers; The lead-in pipe and the inlet end of the acid return pipeline are respectively connected with the highest parts of a plurality of condenser water chambers, the outlet end of the acid supply pipeline is connected with the cleaning tank, and a lead-in pipe is arranged to connect the acid supply pipeline; A valve is arranged at the connection position of the acid return pipeline and the acid supply pipeline.

[0019] In some embodiments of the application, the cleaning system further comprises an acid storage tank, the acid storage tank is connected with the cleaning tank, and the horizontal position of the acid storage tank is higher than that of the cleaning tank. The cleaning tank can be used for preparing and containing cleaning liquid.

[0020] In some embodiments of the application, the cleaning system further comprises a gas discharge pipeline, one end of the gas discharge pipeline is connected with the condenser, and the other end is connected with the cleaning tank.

[0021] In some embodiments of the application, the cleaning system further comprises an acid discharge pipeline. The acid discharge pipeline can be led out from the acid return pipeline and provided with a valve, when the condenser cleaning work is completed, the valve is opened, and the cleaning waste liquid can be discharged to a waste liquid pool through the acid discharge pipeline.

[0022] Compared with the prior art, the application has at least the following advantages: The application significantly improves the descaling efficiency, maximally reduces the equipment corrosion, greatly improves the utilization rate of cleaning agent, reduces the chemical consumption and waste liquid discharge amount, and reduces the environmental load and processing cost of the cleaning process from the source. The cleaning method and cleaning system of the application support the ability of collaborative cleaning of multiple condensers, further amplify the application value in large power stations, and can scale the maintenance cost and downtime. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the specific embodiments or prior art of the application, the drawings needed in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0024] Figure 1The structure diagram of the cleaning system of embodiment 1 of the present application.

[0025] Explanation of reference numerals: 1, cleaning tank; 2, cleaning pump; 3, condenser; 4, acid supply pipeline; 5, acid return pipeline; 6, air release pipeline; 7, acid discharge pipeline; 8, waste liquid pool. DETAILED DESCRIPTION

[0026] It should be noted that the following detailed description is illustrative only and is intended to provide further description of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application pertains.

[0027] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. Unless otherwise stated, all percentages and ratios used herein are on a mass basis.

[0028] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. Unless otherwise stated, all percentages and ratios used herein are on a mass basis.

[0029] In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited. In addition, the terms "mounting", "connecting", "connection" should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be directly connected, can also be indirectly connected through an intermediate medium, can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0030] The technical solutions of the present application will be described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0031] Example 1. Installation of cleaning system Three condensers of the same steam turbine unit have serious fouling on the water side of the heat exchange tubes, which causes the vacuum of the condensers to drop and the terminal temperature difference to increase. The material of the heat exchange tubes of the three condensers is 316L, and the main component of the deposits on the inner wall of the condensers is carbonate scale, with a thickness of more than 7 mm.

[0032] The cleaning system of this example is used for cleaning the three condensers.

[0033] After stopping the operation of the unit and disconnecting the condensers from the system, the outlet and inlet doors of the condensers are closed, and blocking plates are installed behind the inlet door and in front of the outlet door to ensure that they are tightly sealed and do not leak.

[0034] The manhole door on the water side of the condenser is opened, and the heat exchange tubes are cleaned to remove the debris accumulated at the tube openings and to unblock the blocked heat exchange tubes. After the steam side of the condenser is filled with desalted water, the heat exchange tubes are checked for leaks, and if any leaking heat exchange tubes are found, blocking measures are taken.

[0035] The manhole doors of the condenser are closed, a temporary cleaning system is erected, and it is connected to the condenser. The schematic diagram of the cleaning system of this example is shown in Figure 1 The inlet end of the cleaning tank 1 is connected to the inlet end of the cleaning pump 2, the outlet end of the cleaning pump 2 is connected to the inlet end of the acid supply pipeline 4, the two outlet pipes and the outlet end of the acid supply pipeline 4 are respectively connected to the water chambers of the first condenser 3, the second condenser 3, and the third condenser 3, for example, to the interfaces of the lower water chambers of the condensers. The inlet end of the acid return pipeline 5 and its outlet pipe are connected to the uppermost interfaces of the upper water chambers of the condensers 3 to prevent the condensers 3 from not being able to maintain a full state during cleaning. The outlet end of the acid return pipeline 5 is connected to the cleaning tank 1, and an outlet pipe is connected to the acid supply pipeline 4. Valves are also provided on the connection pipeline of the outlet pipe of the acid return pipeline 5 and the acid supply pipeline 4, and when the acid return liquid can be used for cleaning the condensers, the corresponding valves are opened. The uppermost part of the upper water chamber of each condenser is also connected to a gas discharge pipeline 6 for discharging waste gas generated during the cleaning process. The outlet end of the gas discharge pipeline 6 is connected to the cleaning tank 1.

[0036] The cleaning system also includes an acid discharge pipeline 7. The acid discharge pipeline 7 can be branched from the acid return pipeline and provided with a valve. When the condenser cleaning work is completed, the valve is opened, and the cleaning waste liquid can be discharged to the waste liquid tank 8 through the acid discharge pipeline.

[0037] Pressure gauges and sampling pipes are installed at the inlet end of the acid supply pipeline 4 and the outlet end of the acid return pipeline 5 to monitor the pressure during the cleaning process and the acid concentration of the cleaning liquid and the acid return liquid.

[0038] After the installation of the cleaning system is completed, industrial water is injected into the cleaning system, the cleaning pump is started, and a pressure test is performed to check for leaks and defects.

[0039] Condenser tube test ring (condenser heat exchange tube sample) is hung in the condenser water chamber of the condenser by corrosion-resistant insulated rope as corrosion indicating tube for monitoring the cleaning and corrosion of the condenser during the cleaning process.

[0040] Example 2. Circulating cleaning of condenser This example uses the cleaning system of example 1 to synchronously clean the first condenser 3, the second condenser 3 and the third condenser 3.

[0041] (1) Preparation of cleaning solution The cleaning solution with the mass concentration of nitric acid of 4% and the mass concentration of Lan-826 of 0.3% is prepared by industrial water and added into the cleaning tank 1 (the volume is 8 cubic meters).

[0042] (2) Circulating cleaning The cleaning pump 2 is started, and the cleaning solution is circulated according to the flow of cleaning tank 1→ cleaning pump 2→ acid supply pipeline 4→ condenser 3→ acid return pipeline 5→ cleaning tank 1, and the cleaned space includes the water side and water chamber of each condenser 3 and the connecting pipe and temporary pipeline thereof; the cleaning volume of the three condensers is 150 cubic meters in total. The cleaning flow rate is controlled to be 0.2 m / s by the power control cabinet of the cleaning pump 2, and the pressure is not more than 0.1 MPa.

[0043] The first condenser 3 and the second condenser 3 are connected in parallel and cleaned at the same time, and the nitric acid concentration in the liquid at the inlet (the inlet end of the acid supply pipeline 4) and the outlet (the outlet end of the acid return pipeline 5) of the system is detected every half an hour. When the nitric acid concentration in the acid return liquid at the outlet of the system is less than 3%, nitric acid and corrosion inhibitor need to be supplemented, the corrosion inhibitor is added into the cleaning tank 1 and circulated uniformly, and then the nitric acid is supplemented, so that the nitric acid concentration in the cleaning solution at the inlet of the system reaches 4%. When the acid concentration at the outlet of the system is greater than 3%, the acid return liquid in the acid return pipeline 5 can be directly introduced into the third condenser through the acid supply pipeline 5 to clean the third condenser. No significant corrosion of the condenser tube test ring in the cleaning tank 1 is found during the cleaning process.

[0044] After 3h, the nitric acid concentration in the liquid at the inlet (the inlet end of the acid supply pipeline 4) and the outlet (the outlet end of the acid return pipeline 5) of the system is detected every 10 minutes, and the corrosion inhibitor and nitric acid are supplemented when the nitric acid concentration in the acid return liquid at the outlet of the system is less than 3%.

[0045] When the acid supply and return concentrations approach equilibrium and are greater than 2.0% or the acid concentration is continuously stable for 2 hours and no gas is generated in the acid return liquid, the cleaning endpoint is reached, and the cleaning is stopped. The cleaning time of each condenser is about 4h. About 8 tons of industrial nitric acid (98%) and 550 kg of corrosion inhibitor are used in the cleaning process. The cleaning waste liquid is discharged to the waste liquid tank through the acid discharge pipeline for neutralization treatment.

[0046] After the test, the metal surface of the first, second and third condensers is clean after cleaning, and there is basically no residual hard scale, and the scale removal rate is excellent, reaching 99%, 98.8% and 97.9% respectively. The average corrosion rate of the condenser tube test ring during the cleaning process is less than 0.1 g / m 2 ·h, and the total corrosion amount is less than 1.0 g / m 2 .

[0047] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for circulating cleaning of a condenser, characterized in that, Includes the following steps: S1: Fill the steam side of the condenser with condensate; S2: Prepare a cleaning solution in a cleaning tank, the cleaning solution comprising acid and corrosion inhibitor; S3: Pump the cleaning solution into the condenser through the acid supply pipeline so that the water side of the condenser is filled with the cleaning solution. S4: Cleaning is performed with a cleaning fluid flow rate of 0.1 to 0.25 m / s, and the generated acid return solution is recycled back to the cleaning tank or the condenser for reuse via the acid return pipeline; S5: When the acid concentration in the cleaning solution is lower than the specified value, acid is added. The acid addition includes first adding the corrosion inhibitor and circulating it evenly before adding the acid. S6: Stop acid washing when the acid concentration in the acid supply line and the acid return line is close to equilibrium, the acid concentration is stable for 2 hours, and / or no gas is generated in the acid return solution.

2. The method according to claim 1, characterized in that, The temperature of the condensate is ≤25℃.

3. The method according to claim 1, characterized in that, The cleaning solution comprises 3%-5% nitric acid and 0.2%-0.5% corrosion inhibitor, and the specified acid concentration in the cleaning solution is 3%.

4. The method according to claim 1, characterized in that, The cleaning solution includes 3%-5% nitric acid and 0.3% Lan-826 corrosion inhibitor.

5. The method according to claim 1, characterized in that, During the cleaning process, the acid concentration was checked every 30 minutes, and then every 10 minutes near the end.

6. The method according to claim 1, characterized in that, When multiple condensers are cleaned simultaneously, if the acid concentration in the resulting acid return solution exceeds the specified value, the acid return solution will be recycled to other condensers for reuse.

7. The method according to claim 1, characterized in that, The method further includes filling the steam side of the condenser with demineralized water and checking for leaks before step S1.

8. The method according to claim 1, characterized in that, The method further includes flushing the water side of the condenser with circulating water after step S6.

9. A condenser circulating cleaning system, characterized in that, The cleaning system includes a cleaning tank, a cleaning pump, an acid supply pipeline, and an acid return pipeline. The inlet of the cleaning pump is connected to the cleaning tank, and the outlet of the cleaning pump is connected to the inlet end of the acid supply pipeline; The lead-out and outlet ends of the acid supply pipeline are respectively connected to multiple condenser water chambers; The outlet and inlet of the acid return pipeline are respectively connected to the highest part of the multiple condenser water chambers, and the outlet of the acid supply pipeline is connected to the cleaning box, and an outlet is provided to connect to the acid supply pipeline. A valve is installed at the connection between the acid return pipeline and the acid supply pipeline.

10. The cleaning system according to claim 9, characterized in that, The cleaning system also includes an acid storage tank, which is connected to the cleaning tank, and the horizontal position of the acid storage tank is higher than that of the cleaning tank.

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